Shortcut Methods
Shortcut Methods and Tricks to Solve Numericals on Conductors, Semiconductors, and Insulators:
For JEE Exams:
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1. Use the formula: R∝L/A
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New Resistance = 4R
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2. Dynamic Resistance (rd) = (Change in Voltage)/(Change in Current)
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3. Capacitance (C) =εA/d
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4. Conductivity (σ) = 1/Resistivity
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5. Collector Current (Ic) = Common-emitter Current Gain (β) × Base Current (Ib)
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6. Maximum Power Output (Pmax) = Efficiency (η) × Incident Light Power (Pin)
For CBSE Board Exams:
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1. Resistance (R) is directly proportional to the length (L) of the conductor.
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2. Temperature coefficient of resistance (α) = ((R2-R1)/(R1×∆T))
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3. Capacitance (C) of a parallel-plate capacitor is inversely proportional to the distance (d) between the plates.
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4. Resistance (R) of a metal wire is directly proportional to its length (L).
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5. Dynamic Resistance (rd) = (Change in Voltage)/(Change in Current)
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6. Collector Current (Ic) = Common-emitter Current Gain (β) × Base Current (Ib)
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7. Conductivity (σ) = 1/Resistivity
